EFESTO is a project funded by the European Union H2020 program aiming for a revamp and growth of European know-how and systems engineering capabilities in the strategic field of Inflatable Heat Shield technology for re-entry vehicles. This project analyzes the use of Inflatable Heat Shields for Mars exploration and Earth re-entry applications that served as representative study-cases. In addition to design activities at system and sub-system levels, the EFESTO team focused on testing the aerothermodynamic properties of the Flexible TPS and the mechanical characteristics of the shield, the latter exploiting a manufactured high-fidelity Inflatable Structure demonstrator. The data gathered from the two test campaigns additionally served for experimental-numerical rebuilding and cross-correlation. Finally, a phase-0 feasibility study defined a preliminary IOD mission design to enable in-flight verification and validation of the critical technologies. This paper will present the whole excursus of the project, including the key phases of use-cases survey and investigation, mission scenarios definition and analysis, system engineering and sub-system design, technology development and ground demonstration, future roadmap identification with reference IOD feasibility analysis and early definition. The project achievements have improved the European TRL of Inflatable Heat Shields from 3 to 4/5, thus paving the way towards further developments in the mid-term future. This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 821801.